Sound-transmitter.



f. M. DURKBE & J, B. MILLET.

SOUND TRANSMITTER. H APPLIOATIONIILED 00129, 1904.

966,534 Patented Aug. 9, m0

2 SHEETS-SHEET 1.

45 m 44. w/ KATNEEEEIE:

P. M. DURKEE 8; J. B. MILLET. SOUND TRANSMITTER.

PPLIOATION FILED 00T.29. 1904.

mfim. v Patented Aug.9,1910.

2 SHEETS-SHEET 2.

carries s ra'rns PATENT @FFEQEEL FREDERICK M. DURKEE, 0F NEVITON, ANIO JOSIAH 33. MILLE'E', Old BOSTON, MASSACHU- SETTS, ASSIGNGRS T9 SUBMARINE SIGNAL COMPANY, 015 WATERVILLE, IriAIN'E, A.

CORPORATIGN 0F MAINE.

SOUND TRANSMITTER.

Specification of Letters Eatent.

Application filed ()ctober 29, 1804.

being had to the accompanying drawings,

forming a part of this specification, in explaining its nature.

One object of our invention is the con structicn of a sound transmitter peculiarly sensitive to such. sounds as are best adapted for submarine signaling purposes, while insensitive or practically unresponsive to all other sounds.

Another object of our invention is a transmitter within which the action of the soun'l waves upon the diaphragm is reinforced or amplified to give increased sound effects.

A further object of our invention is a sound transmitter the sensitiveness of which is not impaired by the deadeni g" or dampening efiect of variation of Water pressure during submersion, although the diaphragm be in direct contact with the sea water.

' Another object of our invention is a means of assuring constant and reliable operation of the transmitting microphone by prevent aching of the carbon particles.

Other objects of our invention Wii here inat'tcr appear.

The first object of our invention is based upon the principle that'soundg: inorder to have the best carrying quality in wa ermust be of high pitch, experience having demonstrated that sounds of low pitch are distinct at short distances only. Sulunarine signaling apparatus is accordingly designed to produce sounds of high pitch. ()n the other hand, those sounds and noises of local origin at the receiving station, such as tend to neutralize and confuse signals, are for the inost part of low pitch. life have conceived ,that by making the. receiving diaphragm oi the transmitter selective in its action and responsive to sounds of high pitch only, the signals would be much clearer and consequently audible with certainty at greater distance.

"atented Aug. Q, 191%.

Serial 1V0. 230,510.

()ur transmitter diaphragm is rendered selective by mounting the same under considerable tension. A diapln'agm so held has substantial vibration in response to notes of high pitch only. Our preferred method of so mounting and maintaining the diaphragm consists in heating the same, and while heated, soldering it at its edges to the transmitter casing. The diaphragm being thus held unyieldingly at its edges becomes extremely taut by virtue of its contraction on cooling.

' By restricting the action of the diaphragm to Within certain limits, we have accomplished another purpose. We are enabled to reinforce the action of the diaphragm by means of a column of air or other fluid in contact therewith, and of the pitch. Herctofore Where the diaphragm has had wide range of pitch, it has been impossible to reinforce the same by a column of air except perhaps for a single note. This is be cause such a column has a pitch substantially invariable, and will not respond to sounds of other pitch. A reinforcing means of the charactermentioned it used in conneraion with transmitter diaphragm of usual type, thus responding to certain notes only would be less desirable than none at all h rause of the sudden variations in quantity of sound that would result therefrom. For these reasons, the ordinary telephone transmitter lacks the reinformzment feature, but even with it, would nut be operative to produce improved results.

A common defect of a transmitter when put to submarine use is that its action is deadcned or dampened by the pressure of water on the (liaphragn'i, and this trouble naturally increases with the depth at which the instrument is employed. The diaphragm being pressed inward by the water pressure ordinarily tends to force together the disks between which the carbon resistance varying means lies, and, by packing the carbon, to. cause the responsiveness of the microphone to be impaired. Attempt has been made to rectify or neutralize the fault by adjusting the resistancevarying means to operate elliciently when the diaphragm is thus subjected to pressure. Such adjustment, however, has always been made before submersion of the instrument, and for definite pressures only.

Consequently the result of any variation of the. pressure during subn'iersion, such as by raising or lowering the transmitter, has been to impair the etlicicncy of the instrument. ()n the contrary, in transmitters of the type hereinafter to be described by us, variation of the pressure of the water against the diaphragm cannot operate to pack the carbon or to otherwise. injuriously affect the operation of the microphone.- We have. provided means whereby there. is relative movement of the. disks between which the carbon is located. only at the time of receiving signals. At other times the disks are mounted to yield together in response to Water pressure, and by so yielding together, to prevent packing or displacement of the carbon.

The manner in which we attain the. various objects of our invention will appear upon a more detailed description of the same in connection with the accompanying drawings, in whicln Figure 1 is a. View in sectional elevation ofour transmitter; Fig. a rear view in ele- ."tll'lOll ot the same with the cover piece re- 'n1oved. Fig. 3 isa plan. in sectional elevation ot'a modified form of our invention.

Referring to the rawings; we have shown our ransmitter case 1 comprised ot' two sections, 3 and thrcadedat- 5 to engage one another. the joint between the two being rendered water tight by a rubber or other washer 6. The transmitter case is supported upon the suspension cord 7 by means of an extension 8 threaded to engage the sleeve 5) on said cord. The sleeve 9 is provided with a rubber or other plug 0 packing 10 for tightly holding the suspension cord and providing a Water tight connection therewith and this plug is maintained in position within the sleeve 9 by means of a brass'washer or piece 11. The, extension 8 of the casing is screwed into the sleeve 9 and into contact with the rubber 10 and is so held in place by means of a loclrnut 12 threaded" thereon.

. The suspension cord shown is composed of rubber or other elastic or yielding material whereby it may out transferring riln'ation to thctransmitter. Within the cord are the Wires 13 and 13' forming the transmitter circuit. These wires in order that they may not be injured becai-ise i the flexibility ot the cord, and. that they mayinot impair the flexibility of the cord, are fine. and within the cord are more or less coiled or sinuous, so as to have sufiicient length to prevent thei' rupture, though the cord be somewhat attained or stretched. From the cord 7 the wires are led into the chamber 14 within the transmit-- ter casing. This chamber is to .t-hc most, part formed within the piece 5; or he casing as shown in the drawing and is closed to the water by means of the piece 4-. Within be pulled and jarred with body or section 3 of the casing is also pro vided a. second chamber 15.

At the outer 'end of the flange 17 of the casing, and closing the mouth-of the charm her 15, is a sound receiving diaphragmlti.

This diaphragm is soldered while expanded under heat into its position on the casing, and upon contraction is tautiy stretched across the-mouth of the chamber 15. At the center of the diaphragm 18 is supported the microphone or resistance varying means 19. The resistance varying means itself is within the chamber 14, which is just of su'i'tieient threaded sleeve oi insulated material such as hard rubber or ivory, to prevent ground of the current throigh the lock. nut 25 prevents the microphone turning or becoming loose in the sleeve The microphone is shown as comprising a. cup -shaped member 26. having an out1- *ardly turned flange 27. li ng against the flange 27 and closing the iher is disk 28 of mica orsiinilar niaterii'il. ho disk 28 is retained in place against iangc 27 by a clamping ring Q9. Supper.- ing the disk 28 isthe button ormember in This member 30 is perforated. at 30 to provide for the support Integral with the SUPPOI L 22 within the microphone cas' ing is the plate 31. Secured to the piste 31 is a carbon disk 32. Secured to the membet--26 as at 33 is a carbon disk Between the disks 3'2 and 34 is the resistance var ing means or granular carbon 35. The disks 32 -and 3i together with the carbon between their. are closely embraced by layer 3-6 of fibrous material such cotton or glass Wool which occupies the space between the resistancevarying eiements and il1( ClICl.'SIIlterenee or Wall 37 of the cup 26.- ilonduch ing wires 13 as shown are attached to the cap member 26 which is of brass or other suitable material, While the wire 3.3 is attached to the member 30 of siiniiar material.

It is important that the, transmitter tas ing in the structure shown by us be perfectly watertight. Otherwise the etiiciency of the resonance chamber-will be destroyed by the admission of Water, and the microphone in jured, grounded or short circuited from the same cause. Accordingly asalready stated.

the rubber washer or packingfiis to prevent any access of the outer Waterv tothe chamber 14 through the casing, and the rubber lltl washercr plug 10.to prevent any water reaching the chamber through the extension 8 along the suspension cord. Inorder, however, to positively insure a perfectly water tight casing we have made provision for testing the joints'ot the same. In Fig. 1 the member 3 of7 the casing is shown as having a passage or inlet 42 threadedat its outer end 43. Threaded to engage and close this passage is shown a screw plug 44 the head of which lies in a countersink 46 in the member Beneath the head of the plug is a rubber or other washer 47 to hermetically close the passage 42 when the plug in place. After the transmitter has been assembled and before the instrument is used the plug 44 is removed and the interior of the transni'iitter placed in communication through the passage 42 with a suitable source of fluid under compression. By this means not only any leak in the casing exposed, but, what is more important, the column of air or other fluid within the cas ing' and in contact with the diaphragm may be so adjusted in'density or pressure, as to act in harmony with the diaphragm when vibrating having regard to the depth at which the instrument is to be used. Vhen the proper relation has been established between the fluid within the casing-and the diaphragm the plug 44 is screwed into place. Any other insulating fluid may be substi 'tuted for air it desired.

The structure shown in Fig. 3 is identical to that shown in Fig. 1 with the exception of the manner 'in which the microphone is mounted within the chamber 14. \Vhereas in Fig. 1 the resistance varying means is of the inertia type and is mounted entirely upon the diaphragm 18, in F ig. 2 the resistance means, although shown supported j by the diaphragm 18 as before, isalso provided with a so-called solid back of peculiar construction. In this modification the member 28 of the micrpphone casing has mounted thereon an iron rod or stud 38.- Upon the casing member is rigidly mounted the rod .r invention and the elements thereof are isinitter is lowered or ner by means of the rubm cord '4'. i rli'hough water, the transmitter is of course equally adapted to be immersed in a submerged tank of any liquid and to receive Vibration from the water through the medium of the liquid within the tank, as described in U. Q. Patents Nos. 768,568 and 768,570. The transmitter being lowered in the water the pressure upon the diaphragm l8 gradually becomes greater, but, where in the ordinary transmitter this pressure would tend to force the carbon disks 32 and 34 together thereby. packing the carbon 35 between them, in the case oi our invention the two disks yield inwardly together because they are both supported upon the diaphragm in the manner hercinbefore described. .lhe inertia of the microphone, however, is such that the sharp action of the sound waves upon the diaphragm causes the two disks to have relative movement, and the resistance varying means to be thereby operated, causing pulsations of current in the receiving circuit. This circuit is traced from the wire 13, through the :asing 26, carbon disk 34, carbon 35, carbon disk 32, plate 31, extension 22, plate 30, and wire 3. The ivory or rubber insulating sleeve 24, as hereinbefore stated, prevents grounding of the current 'by the diaphragm 18. The effect of the cotton fiber or glass wool 36 is to provide an elastic support or retaining means for the granulated carbon.

The cotton has suflicient elasticity to yield to any undue pressure or tendency there the same from suffering deterioration by virtue of absorbing moisture or exposure to -the air. The casing 37 has the further efiect of maintaining the fiber truly and unyieldingly in place whereby its proper action is further insured. The disk of mica 2,8 lying between the cup 26 and plate 30 prevents access of air and moisture to the fiber and carbon. between the edge of disk 30 and As hereinbefore mentioned, the diaphragm 18 is tautly mounted over the casing and its tension is such as to make it especially responsive. to sounds of high pitch. The pitch provided for is that at which ctiective submarine signal apparatus is sounded. The diaphragm is but little if at all responsive to the noises or sounds of local origin such as originate within the ship or recz-riving slatioii itself. or to any other sounds except those of the signal bell; The chamber 15 is or" such size that the Fluid column therein vibrates at the pitch to which the diaphragm desitrned to vibrate. The vibrationsoi? the diaphragm and fluid being thus in syn-- .chrony reinforce each other and increase the Vision 22, platelio, wire it's".

artion oil the diaphragm upon the resistance varying moans.

It has boenstatod that the (litllllbtl ld is as, small as possible to hold the microphone and poi'iiiit of tho propor aotion of the saint. One reason for having the t'llflllllKl' of Hlll'll roabrictvd sir m is; to render the ilifill'llllllllt roiiipavt. .tnothor rrasoin howovvr, that they (flltlllllitlh l4 and l? tll't in communication as at it. and as tho (i):lliillll' 15 is usperially dvaignvd to vibrato with the diaphragm, it is dosirahh not to have its piti-h :itl'ortod by (Oillllillliit'zltltill with a large (oluiiiii of tluid such aH might be i-oiitaiuvd in a large rhauihor 14.

Th0 struvturo shown in Fig. It in in all resprrta SllllllRP-l'fi operation to that shown in Fig. 1. except in the provision of tho toniporary solid harli lieroinhvforo dosrrilwd.

its in the sl-rurturo shown in Fig. l the" HHLTOPliODt. casing and its connvutionsi are all mounted upon tho'diaphragm 18 by the. means tlt.(l'll')0t.l. In this figure the receiving circuit may be traced as ollowa:--wire 13, olertroinagnot 41. casing 26, disk 34-, grai'iular carbon 35, dish 32, plato Si, exten- The plate 26 is, however, of modifiqd form, being provided with a Stud 01' rod of metal au fh as iron. 90 long as no Signal being received by the operator there is no current in the ll'lt'ill (in euit' and the microphone yields with the dia- 1')ll1Zl{IH1 to the pressure of tho outer water,

the stud 3 slipping it'reoly betwoan the! prongs oi the yoli'oor fork -40 on the rod -t-l, Upon the ostahlialiiuon't ot' a current in tho lino hythe operator for llit transmission ot signals. howovon the magnet it in said cireuitis viivrgizod, and arting uiagnativally upon thestud f-h oporatvato maintain the vaaiiig 2t? and carbon disk 25+ immovable. Tilt 'iiiovoinont of tho carbon disks 1H and 32 toward (Eltfll other in response to sound waves in than no longer rolatiw or dil'l'rrviiiial as in an atrurturo of Fig. 1 but is positive with the ltSlllt that the sound offocta in the local rirruit are porhapz-i inoi'e sharp.

Although the ahove is a description of the most satisfartory oinhmliiuont, of our ilH'tlitioii now known to us, it is apparent that in dotziil thrstruvturo shown may ho niodiliod without departing from tho apirit thorbot'.

e are awaio otllio patent to Uanirl Drawhaugli. No. MOJHEI, dated June 11.,

and hold tautly strtohod by virtue of its contrariion on cooling.

:0 pitrh in prefer.

3, A'trai'iauiitter havinga diaphragm ar i-aiigod to vibratoat high pitch, a chamber closed by Hilltl diaphragii'i, said chamber of a size to have tho column of fluid theroin:

vibrate at high pitrh in unison with diaw phragni to .roiniorre tho latter.

4. A. transmitter having a diaphragm of definite pitch-inolosing a tPOllllllIl of fluid of substantially the saint: pitch whereby the two vibrato in unison to reinforce each other and enlarge the sound effects on the inier pliono.

in a transniittor, two disks, resistance varying means between the same, a dia phragm in connection with one of said disks, said disks being mounted to yield together with said diaphragm undor normal C(Jllditions, and means for rendaringr one of said t'lislrs'tationai v for the reception of signals. (t. In a ti'iiiisiiiitter, two disks, resistance varying means between the same, a diaphi'agin in (:oiinmi-t'ion with one of said disks, said dialigheing mounted to yield together with said diaphragii'i under normal conditions, illttlliri wi'itrollod. by the operiiitors re (airing vim-nit for roncei'ing one of said disks tllrvltlllillg for the rot-option of signals '4'. in a traiisiiiittor, i'rswtarnro varying iiioaiis a chamber in which said means is (:losoly rontaiilvd, a round receiving dish phragnna ruminating vhaiiihvr vloaool by said diaphragm, a partition hotwooii said chamlltl'SJwilltl diaphragm i-oniniiinitiating through the two (llillillitl'S and :lilltl partition with S In a tllYlt'L? tor rim-hiring subnn'irino siguals', a water tight case adapted to he subinorgod, a high pitch diaphragm closing oiiv sido of the same, a iiiirrophoiio behind said diaphragm in operative connection llltl'lWYilll. and a lth'filmlll'l chamber, and lill'tlilh tor minim-ting the iwouaiive ohan'iber with a lluiil supply wlu'i'oln the fluid p1tS- sui'v in mid rhan'ihoi' may no adjusted, comprising an opening in h'fllll vase leading into Ill) said chamber, and a closure for said opening, said means comprising an opening in said .as described.

10. A transmitter comprising a casing and a diaphragm of definite pitch and in 5 closing a column of fluid of substantially the same pitch with said diaphragm, and means for regulating the pitch of said fluid column whereby it and the diaphragm may vibrate in unison to reinforce each other and 10 enlarge the-sound efi'ects on the microphone,

casing adapted to be connected to a source of flllld under pressure, and a closure therefor, as described.

FREDERICK DURKEE. JOSIAH B. MILLET.

In presence of HORACE B. GALE, A NNIE J. Convnnsn. 

